Among all general electronic devices, the most of them are provided with a heat-dissipating system for decreasing the high temperatures generated under the operation state, so as to upgrade the integral operation efficiency. More particularly to the computer devices, for effectively upgrading the operation efficiencies of all electronic components within the computer devices, the most of the computer devices are provided with a fan and a thermal module. The thermal module is applied to absorb heat generated from the electronic components by heat-conduction under the operation state, and then the fan can rotate to generate convectional airflows, so as to dissipate heat, which is absorbed by the thermal module, to the external environment via the airflow.
For example, when the present computer system is under an initial operation state, such as a booting state, a power supply directly supplies the power for driving the fan, and then the computer system starts to monitor the power supplied for driving the fan after an initialization setting of a basic input/output system (BIOS) is completed. However, the conventional power supply usually sends out a nominal power in a high voltage of 12V, so that the fan operates in a higher rotation speed and generates more noise in the initial operation state.
Following up, above description is further combined with a drawing for progressive illustration. Please refer to FIG. 1, which illustrates a functional block diagram of a conventional fan control system applied to a computer system. As shown in FIG. 1, a fan control system 1 is applied to a computer system, and comprises a power source 11, a fan circuit module 12 and a monitoring unit 13.
The power source 11 electrically connects to the fan circuit module 12, so as to output a nominal power to the fan circuit module 12 for driving a fan (not shown in FIG. 1) therein. The monitoring unit 13, usually being the BIOS, electrically connects to the fan circuit module 12 for monitoring the operation of the fan, and sends a control signal S1 to the fan circuit module 12 according to a monitoring result monitored from the monitoring unit 13, so as to control the rotation of the fan.
When the computer system is under an initial operation state, i.e. under a booting state, the power for driving the fan must be directly supplied by the nominal power output from the power source 11. Due to that the nominal power usually is usually provided in a relative high voltage of 12V, the fan is driven to operate in an extremely high rotation speed and generates a louder noise. Meanwhile, under the operation state of the fan, monitoring unit 13 continuously monitors the operation of the fan and continuously sends the control signal S1 to the fan circuit module. However, in practice applications, it is necessary to go through a steady-time period to make the control signal S1 sent from the monitoring unit 13 control the fan to steadily operate in a relative low rotation speed, so as to reduce noise generated from the fan.